Summary
Queries RDAP registries directly to check domain availability without scraping or API keys. Exposes three tools: check single domains, bulk check up to 50 at once, or generate smart suggestions from keywords that return variations across .com, .io, .ai, .dev, and .co with common prefixes. Uses Verisign RDAP for .com/.net, PIR for .org, and rdap.org for everything else. Runs as a remote server on Fly.dev so there's nothing to install locally. Useful when you're naming a project, validating user input for domain fields, or building registration flows. Also works as a standalone REST API with OpenAPI docs if you need it outside MCP contexts.
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DomainCheckr MCP Server
Check domain name availability instantly using RDAP. No API key or installation required. Works as a remote MCP server.
Quick Start
This is a remote MCP server -- no local installation needed. Just add the URL to your MCP client.
Claude Desktop
Add to your claude_desktop_config.json:
{
"mcpServers": {
"domaincheckr": {
"url": "https://domaincheckr.fly.dev/mcp"
}
}
}
Config file location:
- macOS:
~/Library/Application Support/Claude/claude_desktop_config.json - Windows:
%APPDATA%\Claude\claude_desktop_config.json
Claude Code
claude mcp add domaincheckr --transport http https://domaincheckr.fly.dev/mcp
Cursor
Add to ~/.cursor/mcp.json:
{
"mcpServers": {
"domaincheckr": {
"url": "https://domaincheckr.fly.dev/mcp"
}
}
}
Windsurf
Add to ~/.codeium/windsurf/mcp_config.json:
{
"mcpServers": {
"domaincheckr": {
"url": "https://domaincheckr.fly.dev/mcp"
}
}
}
Tools
| Tool | Description |
|---|---|
check_domain | Check if a single domain name is available for registration. Returns registrar, creation date, expiry, and nameservers for taken domains. |
check_domains_bulk | Check up to 50 domain names at once. Returns per-domain results with summary counts. |
suggest_domains | Generate and check domain name ideas for a keyword or business description. Creates 15 variations across .com, .io, .ai, .dev, .co and common prefixes/suffixes. |
Example Prompts
Try asking your AI assistant:
- "Is coolstartup.com available?"
- "Check if these domains are available: acmecorp.com, acmehq.com, getacme.com"
- "Find me a domain for a pet grooming business"
- "I'm building a fintech app called PayFlow, find me a domain"
How It Works
DomainCheckr uses the RDAP protocol (Registration Data Access Protocol) to check domain availability in real time. RDAP is the modern replacement for WHOIS, standardized by the IETF.
- Queries Verisign RDAP for .com/.net domains
- Queries PIR RDAP for .org domains
- Falls back to rdap.org for all other TLDs
- HTTP 404 = available, HTTP 200 = taken
No scraping, no third-party APIs, no rate-limited services. Direct registry queries.
REST API
The same service is available as a REST API for building your own integrations or ChatGPT Actions.
| Endpoint | Description |
|---|---|
GET /check/{domain} | Check a single domain |
POST /check | Bulk check (body: {"domains": ["a.com", "b.com"]}, max 50) |
GET /suggest?keyword=fintech | Generate and check domain ideas |
GET /health | Health check |
GET /docs | Interactive API documentation |
GET /openapi.json | OpenAPI spec (for ChatGPT Actions) |
Base URL: https://domaincheckr.fly.dev
License
MIT
Featured
Keep your Mac awake while Claude Code and 40+ AI agents run. Sleeps when they're idle.
One time payment $9 →Integrate web data into your AI product. One API to scrape website & brand data.
Get API Key Now →Agent, run crypto. Access onchain data & trade routes via 1inch.
Install now →On Capafy, your Skill runs online 24/7 as an agent product, and you get paid every time someone uses it.
Start earning →